Abrasive device



5 Sheets-Sheet 2 QNNNAN @Ruf 'F. O. ALBERTsoN ABRASIVE DEVICE Filed lay 9. 1938 oct. 11, 193s.

Oct. l1, 1938. |=.'o. ALBER-rsoN ABnAsIvE DEVICE `mm1 my 9. 1938 :s sneetssheet s fzyezazzf [fam 0 melig@ a? Patented i.1 1,193s. I v l 2,132,917

UNITED STATES PATENT OFFICE ABRASIVE DEVICE Frans 0. Albertson, Sioux City, Iowa, assignor to Albertson & Company, Inc., Sioux City, Iowa, a corporation of Iowa Application May 9, 1938, Serial No. 208,738 '4 claims. (ci. 51-197) Thevpresent invention relates to abrasive dewhich is -so constructed that it may be quickly vices, and is particularly concerned with deattached and quickly detached and also so convices adapted to be used for iinisliing and smoothstructed that it will not become so tightly wedged ing operations, such as a pad or support for holdor screwed on the shaft that dimculty will be ing a rotating sanding disc. encountered in its release. 5

The present invention is an improvement over Another object is the provision of an improved that covered by the prior Patent No.- 1,882,693, backing disc which is adapted to give fuller surissued October 18, 1932, to F. O. Albertson and face contact when the sander is tilted and by Gustav A. Olsen for an Abrasive device. means of which clogging of the abrasive is elimi- While the present abrasive device is adapted nated. l10 to be used at any speed, it is particularly adapted A further object of the invention is the proto be used at relatively high rotating speeds, and vision of an abrasive disc-supporting device which for this purpose all of itsparts are made as light is light, sturdy, capable of economical manufacand strong as possible. ture,` and adapted to be used for a long period of In the use of rotating abrasive discs itis found time without necessity for any replacement or 15 that only a portion of the disc adjacent the perepair of its parts. riphery becomes used up 0r filled witngummy ad- Other objects and advantages of the invention hesive materials, such as paint, and it has bewill be apparent irOm the f0110WiI1g deSCriPtiOn come customary to trim on' the periphery of a and the accompanying drawings, in Which Simirelatively large abrasive disc and then apply it to lar charactersof reference indicate similar parts 20 a smaller supporting pad for further use. Such throughOuii the Several views.

trimming operations may, for example, be carried Referring t0 the i'W0 Sheets 0f drawings *1060mout by means of an apparatus of the type shown panying this Specification, in Patent No. 2,066,381, issued January 5, 1937. Fig. 1 is e side elevational view 0f a sanding 2'5 i In order to use up fully such an abrasive disc machine used for driving an abrasive device con- 25 according to the methods of the prior art, it structed according t0 the Present inVentiOn;

has been necessary toprovide a multiplicity of Fig. 2 iS a' front Diari View 0f the abrasive desupporting pads of different sizes, such as, for ex- Vice, partially broken away i0 ShOW internal ample, a 9 inch, 7 inch, 5 inch, and even a 3 structure; l,

inch pad has been used. This involves consider- Fig. 3 iS 8 SeCiiOrial View, taken on the plane 30 able expense, since it is necessary to provide a 0f the line Which paSSeS through the axis 0f the plurality of separate pads of different sizes, and drive shaft of the device, with a relatively Small the devices of the prior art havebeen heavier abrasive disc applied to the support;

than is found necessary in the specific construc- Fig. 4 is a view similar to Fig.` 3, with theA largtion which forms the subject of the present apest form of abrasive disc applied to its support; 35

` plication. Fig.,5 is a view similar to Figs. 3 and 4, with One of the objects of the invention is the proan intermediate size of abrasive disc applied to vision of an improved abrasive disc support which the support; is adapted to be used with. abrasive discs of vari- Fig. 6 is a sectional view taken on the plane 40 ou's different sizes whereby one supporting device of the line 6 6 of Fig. 5, looking in the direction 40 may perform the functions of a plurality of deof the arrows; vices which were used in the prior art. Fig. '7 is a sectional view, similar to Fig. 5 Another object of the invention is the provi'- of the preferred form of the invention, having an sion of an improved support for abrasive discs improved construction ofbacking disc;

, which is adapted to flex at its periphery when Fig. 8 is a similar view of a xnodiflcation'em-I 45 sufficient pressure is applied to it so that the ploying a smaller form ofl the same improved abrasive disc-is resiliently forced against the work backing disc, for the purpose of utilizing smaller to which it is applied. y abrasive discs.

Another object of the, invention is the provision i Referring to Fig. 1, the sanding machine is inofan improved abrasive device which has no dicated in its entirety by the numeral III. It is 50 metal parts, s0 disposed es t0 be likely t0 engage provided with a drive shaft Il (Fig. 3) having an the surfaces which are being pohshed. enlargement i2 adapted to be engaged by a peg Another object is the provision foi an improved I3 carried by a pivotally mounted arm I4 for abrasive disc supporting member having means securing the drive shaft in Xed position when atfor securing the abrasive disc to a ldriving shaft tachirig the abrasive supporting pad. ABISl The abrasive supporting pad is indicated in its entirety bythe numeral I6, and it supports a sheet of abrasive I6. The drive shaft II has an annular shoulder i1 between the enlargement I2 andthe reduced cylindrical portion I8, and it is provided with a still further reduced threaded end I9 for receivinga threaded member 26.

The threaded member 20 comprises a hardened metal member of regular polygonal form in cross section, as shown in Fig. 6, and I prefer to make the external shape or surface of the threaded member 20 hexagonal, the hexagonal exterior be ing indicated by the numeral 2'I (Fig. 6).

The member 20 is provided with the internal bore 22, which has threads complementary to the reduced threaded end I9. YThe length of the reduced threaded portion I9`is such that the annular shoulder 23 never interferes with the threaded member 20 because the threaded portion I9 is amply long for its purpose. y

'I'he threaded member 20 is provided with a head 24, which is circular, as shown in Fig. 2, and which tapers gradually toward the outer edge 25. As the rear side 26 of the head 24 is'at or plane, the front side 21 is, therefore, slightly convex. The head 24 is adapted to be drawn in substantially flush with the outer surface of the abrasive disc I4', due to the shape of the abrasive disc and the shape and structure of the supporting pad I5.

The supporting pad I5 is provided with a hub 28, which is preferably formed of light sheet metal", such as an aluminum alloy, and it may be constructed of a pair of cup shaped members 29 and 30. 'I'he cup shaped member 29 has a flat circular body 3I, which is'provided with a centrally located circular aperture 32 for receiving the reduced cylindrical portion I8 of the drive shaft. It has a cylindrical body flange 33, which extends forward, and a radially extending attaching flange 34, which is provided with apertures 35 for receivingrivets 36.

The cup shaped member 30 likewise has a fiat circular body 31 provided with a hexagonal aperture 36 for receiving the threaded member 20. It also has a cylindrical body 39 and a radially extending attaching flange 40 provided with apertures for receiving rivets 36.

The two cup shaped members 29 and 3D 'are preferably fixedly secured4 together by rivets 36,

and the same rivets may support a radially ex-` tending metal disc 4I, which may be also constructed of an aluminum alloy.

The disc 4I has a centrally located aperture I 42 for passing the cylindrical body 39 of the cup shaped member 30.' It also'has the registering apertures for the rivets, 36', and it may be provided with an offset at 43 for causing the outer portion ofthe disc 4I to project forward slightly.

" The apertures 44 are for the purpose of permitting the portions of the molded rubber disc 45 to extend in the threaded apertures 44 to anchor the rubber to the metal disc 4 I. The rubber pinion. 45 is preferably made of relatively hard, molded rubber, which is cast in place, and which is characterized by its vhardness and resilience to flexure, rather than by its softness.

'Ihe rubber disc 45 is intended to flex, but need not necessarily have any cushioning eiect due to the compression of its parts on the face 46 of the disc. The rubber disc 45 is cast about the metal disc 4I, and it is provided with a plurality of layers of fabric 41, tending to reinforce the rubber disc. Its shape may be circular in plan, and in cross section it may taper, as at 48, to make is provided with a plane surface 46. The thickness of the rubber disc 45 is such that the plane surface 46 projects farther outward than the plane surface 50 on the end of the body ange 31 of the cup shaped member 30. Thus the abrasive disc I6 may be provided with a preformed, molded depression 5I for receiving the head 24 of the threaded member 20, or the depression 6I may be formed by the force applied to the head when the head is driven home to compress the abrasive disc I6 against the face 50 ofv 'the hub. I

'I'he abrasive disc I6 may consist -of any desirable or suitable form of fiber; paper, fabric, or cardboard, provided with a facing of abrasive, and having sufoient toughness to withstand the use to which such abrasive discs are put.

The supporting pad I5 shown in Fig. 3 is slight- 1y smaller in size than ve inches, as it is ininch size. '1

The rubber disc 45 is provided with a cylindrical centrally located aperture 52, which is larger than the head 24 of the threaded member 20 so that the rubber disc will not interfere with the headed member. The face 46 of the rubber pad serves as a friction surface for engaging the rear side of the abrasive disc I6 and the face 50 of the hub for a similar purpose.

The central portion of the abrasive disc I6 is rmly clamped between the flat rear surface 26 of the head and the face of the hub 28, while the outer portion of the abrasivedisc I6 has its rear surface drawn into closer frictional engagement with the front face 46 of the rubber pad 45 by virtue of the action of the headed member 20. 'I'his is particularly so when the abrasive disc .I6 is not provided with any pre-formed depression, but is adapted to be deformed by the action of the threaded member 20.

Referring to Fig. 5, this is another view similar to Fig. 3 of the same supporting pad and an abrasive disc which may be the same one as used in Figs. '1 and 3, before it has been trimmed down to the size of Fig. 3.

In this embodiment of the device, however, the threaded member 20 also supports a resilient ber disc 53, which is clamped in place between the face of the rubber disc 45 and the abrasive disc I6. 'I'he ber disc 53 is of a larger size than the rubber disc 45,`as it is intended to be used to increase the size of the supporting pad. For example, the ber disc 53 may be slightly less than seven inches in size, as it is intended to support the abrasive disc I6 when it is a seven inch disc.

The 'lber disc 53 also has a centrally located aperture 54 for slidably engaging the hexagonal portion of the headed member zo, and n'may have a centrally located pressed recess 55 of sufficient size to receive the head 24. In this case the threaded member 20 engages the abrasive disc and clamps it against the fiber disc 53, andclamps the fiber disc 53 against the rubber disc 45.

Referring to Fig. 4, in addition to the assembly of Fig. 5, in Fig. 4 I have employed an additional fiber disc 56, a larger ber disc 53, and slightly smaller than the nine inch abrasive disc I6. This ber disc 56 also has a hexagonal aperture 51 and a centrally located'pressed recess 58 for receiving a head 24 of'the threaded member 20. In

this assembly th supporting discs 45, 53 and 56` hexagonal aperture.

at its outer edge, but which is reinforced farther in by the discs 53 and I5.

The discs '53 and 56 are preferably constructed of a very tough, light and resilient fiber, which is known to the trade as Phenol Fiber, and which may be purchased on the open market, but for specific purposesthe discs4 53, 56 may be constructed of various types of light, resilient material.

. 'I'he operation of my abrasive device is as fol-v lows:

The abrasive disc I6 may be bought in the nine inch size or may be cut out of sheets of abrasive and provided with the centrally located In the rst instance, the abrasive disc I6 is used with the assembly yof Fig. 4, and after a period of use the abrasive surface of the disc I6 will become worn and probably filled with the results of abrasive action, but only adjacent the outer edge. By the use of a trimming machine, such as that exemplified in my prior patent, the outer edge to the extent of about one inch, for example, may be cut off, then making the abrasive disc about seven inches in y size.

Thereafter it may be applied to an assembly of the type shown in Fig. 5, and again used as a seven inch disc on the same supporting member. When the next trimming has been made, the abrasive disc' may be, for example, a pad five inches in diameter, and it may be directly applied to the supporting pad, as shown in Fig. 3. Thus one supporting pad is adapted to be used with various different sizes of abrasive discs, performing the function of a number of the devices ofthe prior art, at a minimum cost.

Referring to Figs. '7 and 8, these are views which show the preferred mode of use of the invention and the preferred form of backing disc. In this embodiment it will be noted that the supporting pad is of the same construction as that described in respect to Fig. 3.

'Ihe backing disc -10' is preferably constructed of Phenol Fiber, a laminated, synthetic, resinous product which is adapted to resist exposure to moisture or highhumidity. This product comprises laminations of fiber which are impregnated and bound `together by a phenolic condensation compound, and the ber possesses the property of resisting warping or distortion when it is subjected to alternate wet and dry conditions.

The fiber also has a high physical strength soy that it can withstand rough usage, and it is rela-l tion 13, the corner 14 of which is rounded off.

The backing disc has at its center a pressed de- The material must also have a considerable tensile strength, as it is subjected to great pression 15, which is adapted to receive the threaded Vmember 24, and it may be vsecured to the pad in the same manner as the devices previously described. By means of the backwardly turned edge portion and rounded corner 14 a wider surface contact is secured between the abrasive disc and the work surface, and the clog.-

ging of the working surface of the abrasive by the paint is eliminated.

Referring to Fig. 8, this is a similar view, which includes a backing disc 16 'of the same construction, but of slightly smaller size, such as, for example, a disc slightly under seven inches in diameter, to receive the abrasive disc 1I when lit has been trimmed down to the seven inch size.

In the preferred form of the invention only one backing disc is mounted at any time, which increases the flexibility of the supporting pad over that of the pad when a` plurality of backing discs are employed.

' I desire it to be understood that the sizes which have been set forth as examples herein' are merely exemplary and need not necessarily be employed, as the supporting pad and reinforcing discs 53, 56 may be made in different sizes from that shown, or may be used in greater or lesser number.

.It will thus be observed that I have invented an improved abrasive device which is adapted 'to be constructed more cheaply than the devices of the prior art, and which is of a lighter construction, yet it is sumciently strong to be rotated at higher speeds.

By means of the present equipment the abrasive discs of large size may be used and trimmed down and operatively supported upon the same supportingY device. The expense of the complete equipment has been materially reduced by my invention.' n

By means of the present improved backing disc structure, clogging of the working surface of the abrasive by paint is eliminated, and a much wider contact area is secured in relation to the working surface.

AThe present supporting pads are lighter than the devices of the prior art, due t0 the use of only one backing disc at any time in the preferred form of the invention, and they may therefore be rotated at higher speeds without damage.

While I have illustrated a preferred embodiment of my invention, many modifications may be made Without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

l. In a supporting device for an abrasive disc, the combination -of a hub comprising a hollow sheet metal member having a pair of apertures witha resilient, hard rubber disc carried thereby, and a plurality of additional resilient fiber discs of successively larger size adapted to be mounted on said hub, and with an abrasive disc carried on the outside of the largest of said fiber discs, and means for securing all of said discs together to be driven by a common drive shaft, said abrasive disc being adapted to be trimmed at its outer edge and applied to successively smaller discs by the omission of fiber discs larger than the abrasive discs, one-.of said apertures being a circular aperture, and the other of said aperturesy 'being a non-circular aperture, and a threaded member for engaging a drive shaft, sai-d threaded member having,r slidable engagement in said noncircular aperture.

2. In an abrasive device, the combination or a supporting pad having a hub, with an abrasive discv of relatively large size, a plurality of backing discs of different sizes adapted to be selectively used with the abrasive disc as the abrasive disc is trimmed down, and a threaded member for securing the abrasive disc and backing disc to said pad, said backing disc being constructed of laminated fiber impregnated with a phenolic condensation compound, and having a backwardly turned rusto-conical surface adjacent its outer edge whereby clogging of the abrasive is eliminated.

3.v In an abrasive disc, an abrasive backing disc comprising a circular member provided with a plane body portion and a centrally located depression for receiving the head of a threaded member, said body portion carrying at its outer edge a frusto-conical backwardly turned portion for providing an increased area of contact with the work surface, said backing disc beingconstructed of a laminated fiber product impregnated with a phenolic condensation compound.

4. In a supporting pad for rotating abrasive discs, the combination of a pair of metallic, cupshaped members, each having radially extending attaching flanges, and each havingcentrally located apertures, with a radially extending disc of metal secured to said attaching anges by fastening devices, a hard, yet flexible, rubber disc carried by said radially extending metal disc and having integral portions extending through apertures in said metal disc, a plurality of backing members comprising laminated fiber impregnated with a phenolic condensation compound, each of said backing members being of successively larger size, and said bacmng members being arranged with the smallest one adjacent said rubber disc, a sheet of abrasive carried outside of the larger of said backing members, a headed metal member having its head substantially embedded in said abrasive and having a threaded portion, said headed metal member also having a non-circular outer surface engaging in a non-circular aperture in one of said cup-shaped members, the supporting pad and assembly comprising a relatively light abrasive'member adapted to.be rotated at a high speed for abrasive operations.

FRANS O. ALBERTSON.

'Uli 

